Method of elastifying a substrate blank and an elastified substrate blank

ABSTRACT

A method of elastifying a non-woven or plastic jacket of a pants-type article in its unassembled hour-glass form, arranged end-to-end in a longitudinal web, includes the steps of stretching a web length of elastic net, film or elastomeric non-woven material, which is rectilinear in its unstretched state, transversely but not longitudinally at the two end portions (113) which will form the waist, stretching the length of elastic net, film or elastomeric non-woven material longitudinally but not transversely at the intermediate crotch portion (14) therebetween, whereby the net or film will naturally assume the desired hour-glass shape of the jacket to be elastified, then bonding the stretched net or film in its hour-glass shape to the jacket (5).

BACKGROUND OF THE INVENTION

The present invention relates to a method of elastifying a substrateblank and to an elastified substrate blank.

Elastic net or film has been used to elastify pants type articles, suchas diapers, pant diapers, sanitary briefs, incontinance garments etc.GB-A 2 248 380 describes for example a method for elastifying a pantstype disposable article, whereby elastic threads are laid out inalternating straight sections and curved sections corresponding to theleg portions. Separate transverse elastic portions are laid in the waistsections. In general this is a very complicated procedure involving anumber of steps and which are prone to malfunctioning. Nor is itpossible according to this known method to elastify an entire pants typearticle to hold it securely in place against the body of the wearer.

WO 93/18729 describes the application of net elastic strips in straightlines, longitudinally to elastify the leg openings and transversely toelastify the waist portions. This is simpler than the above method butthe straight leg opening elastic strips do not conform well to thewearers legs when worn. As in the above case, such elastificationrequires both transverse and longitudinal laying of the strips and theentire pants type article is not elastified, only the end and side edgeportions.

SUMMARY OF THE INVENTION

These and other problems are avoided by the method of the presentinvention. The method according to the invention makes it possible tolay an elastic net in a simple and reliable manner so that alongitudinal section of a web of elastic netting or film with straightparallel sides will naturally assume the hour-glass shape of the diaperor pants substrate blank and can be afixed thereto. The longitudinallystretched intermediate crotch section will naturally assume the form ofthe leg openings providing elastic threads of elastified film portionsnaturally conforming to the concave leg opening edges, thus providingsecurity against leakage. The waist portions will also naturally assumea substantially straight edge configuration when a series of pantsblanks are elastified end-to-end in a web.

According to a further development of the inventive method, apertures inthe net or film can be provided in a very simple manner at the areaswhich will directly face the anus and the urethral opening when a diaperor pants diaper is worn, by making a simple slit at each desiredlocation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further advantages will become evident from the followingdetailed description with reference to the figures in the drawing ofwhich:

FIG. 1 shows a web net which is elastic both longitudinally andlaterally, and which is slipped in its untensioned state onto pegsmounted on carriages,

FIG. 2 shows the web net shown in FIG. 1 after the carriages have beenseparated from each other in accordance with the invention.

FIG. 3 shows the web net shown in FIG. 2 bonded to a pant-diapersubstrate web after having been stretched, in accordance with the methodof the present invention,

FIG. 4 shows a pant-diaper substrate blank made according to anothervariation of the method according to the invention and wherelongitudinal slits have been made in the net prior to bonding to thesubstrate,

FIG. 5 shows a pant-diaper substrate blank but where two parallelrectangular lengths of elastic net have been bonded to the substrate inaccordance with the invention.

FIG. 6 shows a pant diaper substrate similar to that shown in FIG. 4with an elastic net bonded to the substrate.

FIG. 7 shows the pant diaper substrate with net in accordance with FIG.6 with an absorption unit fastened on the pant substrate.

FIG. 8 shows the pant substrate with net in accordance with FIG. 6 withan absorption unit of a second embodiment fastened to the pantsubstrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a portion of a web net of indefinite length, delivered froma roll for example, which can be rubber or artificial resin fused at theinterstices 2 between the longitudinal 3 and lateral 4 threads. In thiscase it is uniformly elastic both longitudinally and laterally. In otherembodiments it can be advantageous to have different elasticities in thelongitudinal and transverse directions. Woven elastic threads can alsobe used, as well as elastic film, which can be regarded as an elasticnet with infinitely small openings. Non-woven material such aselastomeric melt-blown material can also be used.

FIG. 2 shows a web net portion which has been stretched transversely butnot longitudinally at the waist end portions 13 and longitudinally butnot transversely in the intermediate crotch portion 14 therebetween. Byso doing the originally rectangular length of elastic netting naturallyassumes the hour-glass shape shown in the drawing and it can be easilybonded to the pant-diaper substrate. There will of course be bothtransverse as well as longitudinal tensions in the transitional portionsbetween the waist and crotch portions, with the transverse tensiongradually deceasing as one approaches the middle of the crotch portion.

The longitudinal threads 3 will follow the curved cut-out shape of theleg opening and provide an effective tight seal around the legespecially in combination with the cohesion provided by the transversethreads.

The size of the holes (in this case scuare holes) formed by the elasticthreads is irrelevant. An elastic film, i.e. infinitely small holes,will also assume the hour-glass shape.

FIG. 3 shows an elastic net after stretching, bonded to a pant-diapersubstrate 5. This bonding can be achieved in a number of different ways,such as gluing, e.g. hot-melt adhesive, or heat sealing by ultrasonicbonding or heat calendering.

FIG. 4 shows the same pant-diaper but where the net has been slitted attwo places longitudinally before bonding. Two holes 6 and 7 are therebyformed in the net corresponding to the pockets with absorbent materialfor collection of urine and feces respectively. Such an absorbentarticle is disclosed in co-pending applications Ser. Nos. 9500385-1 and9500386-9. Such slits are very easily made by cutting off a number oftransverse threads when the net is in its stretched state. Thesetransverse threads can also be pre-cut when the net is in itsunstretched state. Certain of the transverse or longitudinal threads canbe cut or pre-cut for other purposes as well, e.g. reconfiguring thehour-glass shape of the net.

FIG. 5 shows an alternative embodiment where two parallel rectangularlengths 8,9 of elastic net are stretched according to the inventivemethod the waist portions are in this case slanted to confrom to theconcave belly edge 10 and the convex back edge 11 of a diaper. Anon-elastified central area 12 is left which can accommodate a centralabsorbent pocket.

By stretching the net or film transversely but not longitudinally in thewaist portions and fixing the net or film to a non-elastic substrate, inthis case the web constituting the pant-substrate blanks, there will bean elastic tension when the pant-type product is worn which actscircumferentially, holding the waist portion against the waist of theuser but without any undesirable vertical tension there which couldcause the waist portions to bunch up. The longitudinal dimension of thewaist portion will be fixed, thus avoiding problems with bunching orsagging in a diaper for example.

And in a corresponding manner, since the intermediate crotch portion isstretched longitudinally but not transversely and fixed to asubstantially non-elastic substrate, it will, when assembled and worn,extert a tension cirrcumferentially around each leg,preventing leakagethere. The longitudinally extended threads in the middle crotch regionremote from the legs may be used to hold the absorbent material in placeagainst the body of the user.

It may be advantageous to use an elastic thread material which retains acertain amount of extension permanently when stretched, i.e. Permanentset. To this end, the method may include the step of stretching theelastic material beyond its yield point to retain a certain amount ofpermanent elongation.

The invention has been described above mainly in relation to an elasticnet, but, as stated previously the invention can be executed as wellusing a plastic film. This plastic film can can be of varying propertiesto provide different performance in the finished pant-type product. Forexample, the film can either be elastic over its entire range ofextensibility from its original unloaded state to its rupture point, or,as is the case with many thin films appropriate for this purpose, it maybecome elastic only after having been extended a certain amount, i.e. inthe transverse direction for the waist portions, and in the longitudinaldirection in the intermediate crotch portion. Or the elastic materialused may be elastic up to a yield point and thereafter elastic butretaining a permanent elongation. This may be useful in creating optimumelasticity and shape of the final product.

The elastic material used can also have different elastic properties,for example different module of elasticity in the transverse andlongitudinal directions to achieve desired elastic properties and shapein the final product.

It should also be obvious to the person skilled in the art that theinvention is not only applicable to disposable pant-type diapers and thelike but to any type of elastic pants, both disposable and thosedesigned to be washed and reworn many times.

FIG. 6 shows a pant 13 formed of a pant substrate of a non-wovenmaterial and an elastic net stretched as the elastic net described inconnection with FIG. 2 and 3.

FIG. 7 shows an absorption unit 14, comprising of two part 15 and 16,where the first part 15 is arranged to cover the urine opening 6 in thepant 13 and where the second part 16 is arranged to cover the analopening 7. The absorption part 15, comprising an outer liquidimpermeable cover 17, fastened at its periphery against the pant.

The space outside cover 17 may be filled with an absorbent, material,such as cellulosic fluff and/or absorbent gel.

The absorption part 16 for feces comprises an outer liquid impermeablecover 18 fastened at its periphery against the pant. The space insidethe cover 18 is preferably empty as it is intended to keep feces insidethe cover.

In FIG. 8 the absorption unit 14, covers both the urine opening 6 andthe anal opening 7. The absorption unit may comprise absorbent materialinside the cover 19.

The absorbent articles according to FIG. 7 and 8 can be modified. Theimportant thing is in contrast to known absorbent article that a pant isformed which pant is in close contact with the users skin all over thepant and proximate the user's urethral opening and anus and that theabsorption unit is arranged on the outside of the pant and held up byit.

The elastic pant can be designed with small holes 6, 7 because they areheld in place and kept open by the elastic properties of the pant.

When feces or urine is excreted they will pass through their respectiveholes and into their respective pockets in the absorption unit.

The urine and feces collecting parts 15, 16 can be fastened to the panttightly sealed to the portions of the elastic pant immediatelysurrounding the respective ones of the holes.

The front pocket, absorption part 15, may be filled and weighted downwith urine without it pulling the elastic pant out of position incontact with the user. Since the two parts 15 and 16 are separated fromeach other the feces and urine will not mix, which is a known advantageto prevent irritation of the skin.

The cover 17 and 18 can be made of elastic material to be able to expandas they are filled with feces or urine. The cover 17 and 18 can also befolded as a bellows which expands as it is filled.

We claim:
 1. An elastic pants type article comprising:an elastifiedsubstrate blank comprising a substrate blank with two relatively widerwaist portions adjacent longitudinal ends thereof, a relatively narrowercrotch portion between the longitudinal ends, and transition portionsbetween said waist portions and said crotch portion, and an elasticmaterial bonded to said substrate blank, said elastic material havingelastic properties in longitudinal and transverse directions and beingstretched at positions corresponding to said waist portions of the blankin the transverse direction but not in the longitudinal direction andstretched at a position corresponding to said crotch portion of theblank in the longitudinal direction but not in the transverse directionand stretched at positions corresponding to said transition portions inboth the directions, the elastified substrate blank being contractedtowards a midpoint: of said crotch portion; and an absorption unitattached to said substrate blank.
 2. The article of claim 1, furthercomprising apertures in said elastic material at a front and a rear ofthe article when the article is being worn.
 3. The article of claim 2,wherein said absorption unit comprises two sections, each of saidsections corresponding to one of said apertures.
 4. The article of claim2, wherein said absorption unit comprises two receptacles, each of saidreceptacles corresponding to one of said apertures.
 5. The article ofclaims 1, wherein said absorption unit comprises at least one of fluff,absorbent foam, and superabsorbent gel.
 6. The article of claim 1,further comprising an impermeable material on said absorption unit. 7.The article of claim 1, further comprising fixing means at edges of saidwaist portions for removably affixing the article around a user's waistwhen the article is worn.
 8. The article of claim 1, wherein saidelastic material comprises one of elastic net, elastic film, and elasticnon-woven material.
 9. An elastified substrate blank for an elasticpants type article, the elastified substrate blank comprising:asubstrate blank with two relatively wider waist portions adjacentlongitudinal ends thereof, a relatively narrower crotch portion betweenthe longitudinal ends, and transition portions between said waistportions and said crotch portion; and an elastic material bonded to saidsubstrate blank, said elastic material having elastic properties inlongitudinal and transverse directions and being stretched at positionscorresponding to said waist portions of the blank in the transversedirection but not in the longitudinal direction and stretched at aposition corresponding to said crotch portion of the blank in thelongitudinal direction but not in the transverse direction and stretchedat positions corresponding to said transition portions in both thedirections, the elastified substrate blank being contracted towards amidpoint of said crotch portion.
 10. The elastified substrate blankaccording to claim 9, wherein said elastic material has different moduleof elasticity in its longitudinal and transverse directions.
 11. Amethod of elastifying a substrate blank for an elastic pants typearticle, the substrate blank having two relatively wider waist portionsadjacent longitudinal ends of the blank and a relatively narrower crotchportion between the longitudinal ends, the method comprising the stepsof:stretching an elastic material that has elastic properties inlongitudinal and transverse directions by stretching the elasticmaterial at positions corresponding to the waist portions of the blankin the transverse direction but not in the longitudinal direction, andstretching the elastic material at a position corresponding to thecrotch portion of the blank in the longitudinal direction but not in thetransverse direction; and bonding the stretched elastic material to thesubstrate blank.
 12. The method of claim 11, wherein the stretching stepcomprises the steps of attaching lateral edges of the elastic materialcorresponding to the waist portions to respective movable sides of aframe and moving the sides to transversely stretch the waist portions.13. The method of claims 11, further comprising the step of slitting theelastic material before the stretching step to form a hole in theelastic material when the elastic material has been stretched.
 14. Themethod of elastifying a substrate blank in accordance with the method ofclaim 11, wherein the elastic material is stretched and bonded to thesubstrate blank when still a part of a continuous rectilinear web ofelastic net, film or elastomeric non-woven material, whereafterindividual substrate pant-blanks are cut from the bonded web.